Dry honing device



Sept. 27 1960 w. H. MEAD 2,953,875

DRY HONING DEVICE Filed Dec. 3, 1957 nap I uana,

INVENTOR. FIG.

- LJ/LL/AM. H. EAD

BY :5 W a ATTORNEY United States Patent My invention relates toimprovements in .means .for

efluidizing any powdered or finely ground material to. facilitate itsrbeingfedrinto an airstream while atthesame time separating ,from thematerial .any heavier particles which :it .may have picked up.

I shall describe .the application of .my invention as a dry powder.feeder .and separator in .a .dry honing .device. By dry honing device,.I .mean .a mechanism which employs an air Stream into which .a meteredamount .of .a -.dry powdered .abrasive is -fed and then impelled by theforce of the .air stream against a surface .tobe cleaned -.or.otherwisetreated. s a

My invention was directed at first to :solving .a problem existing inthe tool and die art where :in finishing a :die

[it :is blasted-to smooth out the grinding vlines. .Anunex- .pectedadvantage of my invention that in'addition to erasing theggrindinglines, the action-of the dry abrasive provided countless tinypockets in the die parts rinwhkh zlubricant is retained, .with .aresulting-longer ,life of idl die.

Another advantage -.of my invention rlies in its use in deburring toolsand machine ,parts vhaving intricate passageways which in the pastserved as'traps .for the abrasive which was used in a-slurry (wet formina fluidetreamt).

The slurry would pack in corners :and crevices, ,makingit practicallyimpossible ,to remove it. The time spent in blowing, washing andscrubbing the part was long and tedious and never completely e'fiective.

A further advantage of being abletoifluidize thezabrasive and to use itin dry form is,that.a.vacuum,pickeuprof the spent abrasive can be usedto get a continuous re-use of the abrasive. This pickup was not possiblewith slurry honing.

Another advantage of being able to fluidize the abrasive prior to itsre-entry into the air stream is that the debris can be settled out andnot be recirculated.

Other objects and advantages of my invention will be apparent from thefollowing disclosure of a preferred embodiment of the device. Thisdisclosure is made in compliance with the statute and is not intended tolimit the form of the parts which may be varied by differentmanufacturers.

In the drawings:

Fig. 1 is a diagrammatic view of the parts comprising the invention, inthe environment of an air blasting device, and

Fig. 2 is an exploded view of certain of the parts.

In Fig. l, a hopper 10 is shown positioned above the feeder fluidizerparts which are in the area at the bottom of the hopper. The hopper 10contains a load of finely ground abrasive which, depending upon the workto be done, may be anywhere from 325 mesh to 5000 mesh.

The feeder-fluidizer includes the feed valve housing 11 with a feed T 12extending vertically through it and terminating at an orifice 13 in thebottom of hopper 10. The end 14 of the T is connected by the conduit 15I ice with thetop of the hopper 10. The other end 16 is :connected tothe vacuum source "(not shown) and beyond that to'the blasting gun ornozzle (shown in dotted'l-ines). Thisproduces a flow of air inthedirection ofgthe arrow .17 which willp'ick up any abrasive particlesWhichtravel downthe leg '18 of .the TI v A vacuum is maintained in thehopper 10 which means that the area 20 in the housing 11 is also underreduced pressure. An air inlet "21 is provided into the housing '11,with a suitable silica-gel moisture trap 22 to-dry the entering thehousing. The .size of the inlet 21 "is fixed to give the air flo,wnecessary to fluidize and *to separate the dry abrasive in the hopper"10.

Supported in the housing 11 is a porous stone partition 23 with a closefit both against the wall of the .housing at ,its periphery, and at 24where ;the leg 18 of the T extends through it. The porosity of the stoneis such ,that'ior the vacuum maintained in the hopper 10, enough air.will flow upwardly through the stone (see arrows in fig. 2) to fiuidizethe fin powdered abrasive in the bot- 'gtom of 1116 hopper 10'. A formof porousstone'i have found useful is jknown on the market as a rosin.guartz vfilter, a product of ,Filtros, Inc., Rochester, NewfYork.

fThe porosity according to the manufacturers description is medium :fineporosity. T his works well With.-a11 aluminum oxide abrasive of a widerange in particle size.

As aresultoi beingffluidizedthe abrasive li r lly fiows -fhrough theorifice13into the feed T at ;12. From there ,theabrasive goestothe'hlast nozzle ,audiis picked up, as

spent abrasive, by the suction line 25 connectedftov the .cyclone26 andthesuction pump 27. The ,spent abrasive 'hasiinitsome debris which itsimp t with the work. sur Iaeereinoyed. 'Largenparticbs of dehrisarettpped on the screen 28 and the smaller particles remain intermingled withthe abrasive powder whieh fallsthroughgthe screeninto.thehQmlerlo.

My invention acc mplishes he removal ;from .th'ea asive of .thesesmaller parti le of debris by having th ai .pervions stone .23 com inewith the orifi e1 which i spacedabove thesuriace o'f theston 13. Whatapp ar ;to;hannen; is that the .air .on leaving the stone .23 b bbles.throughthe abrasive and debris .caus'ingthe latt r to. e e flower inthe.hopper10j'intojthearea below the level or the .orjifice 13. The netresult isthat the abrasive entering the orificem 'is-subs'tantia'llycleaned and is only contaminated with debris to the extent of therelative area of the orifice 13 to the area of the housing 11. If theserelative areas are 1 to 100, then it means the abrasive will be about99% cleaned. This slight contamination is because the debris over theorifice 13 will settle into the tube while the other debris is settlinginto the areas below and beside the orifice 13.

A spring 30 encircling the tube 18 will hold the porous stone 23 in asnug fit on the bottom of the hopper 10.

The above described device thus accomplishes an aeration of fluidizingof the abrasive-debris mixture in the hop per 10, and the difference inspecific gravity of the debris and of the abrasive causes the debris tosettle out of the aerated abrasive. This settling-out can go onefiectively until the area in the hopper below the orifice 13 becomesfilled with debris at which time the machine is stopped and the partsseparated to remove the accumulated debris. This suggests that theorifice 13 should be put at a height which will give the desired lengthof operating cycle between cleanouts.

Briefly summarized, the operation of my device is as follows: The hopper10 is filled with a dry powdered abrasive suitable to the job to bedone. A vacuum is applied to the line 16 to draw the abrasive to theblast gun. This same vacuum, through pipe 15 puts the hopper underreduced pressure, with the result that air is drawn into the hopper 10through the silica-gel dryer 22 and through it the porous stone 23. Thisair fiuidizes the abrasive in the hopper 10 with the result that some ofit enters the orifice 13 and travels down the leg 18 into the air streamto the blast nozzle. The abrasive loosens debris from the surface beingtreated and this with the spent abrasive is sucked into the cyclone 26where it falls onto a vibrating screen 28. The large particles of debrisare caught by the screen. The smaller particles go with the abrasiveinto the hopper 10. Here, the upward moving air current through theporous member 23 fluidizes the abrasive-debris mixture, causing thedebris to stratify into a layer below the orifice 13, simultaneouslylifting the abrasive above it and causing the abrasive to flow easilydown the leg 18 of the feed T 12. This fluidizing of the abrasive makespossible a metering feed of it to the blast gun and an effectivecleaning of the abrasive as the continuous blasting goes on.

In brief what happens is that the dry abrasive powder is fluidized so itcan be metered to the feed T 12, while the debris brought back from thework with the spent abrasive is settled out in the area below theorifice 13.

The area of the stone 23 and its porosity will be chosen with the sizeof the abrasive and the size of the blast gun in mind. The same is trueof the size of the feed orifice 13. The height of the orifice 13 abovethe stone 23 will be regulated by the length of runs between shutdownsto clean out the debris. The porosity of the air pervious member 23 canbe selected on the basis of the upward air flow needed to produce thedesired aeration of the abrasive and the settling out of the debris.

While I have mentioned the use of air pervious stone for the part 23, itis possible to use other air pervious materials which will have anequivalent operation in the device.

The tube 18 may be made adjustable in height in the bottom of the hopper10 by any well known expedient,

such as by the use of a slip joint sealed by an O ring or the like.

What I claim is:

1. In a dry honing device for treating the surface of materials withfine abrasive particles contained in an air stream, including a sourceof air under reduced pressure, a feed hopper for said abrasiveparticles, also connected to the aforesaid air source, a blast nozzlefor directing said particles at said surface, the device for feedingsaid abrasive particles to said nozzle being characterized by a housingsecured at the bottom of said hopper, an air inlet into said housing, anair pervious partition separating said housing from said hopper, saidpartition formed from a porous material having a large number ofirregular tortuous passages, the porosity of said partition being chosento give the desired air fiow from the air inlet up into the hopper,while preventing downward flow of the abrasive particles through thepartition when no air is flowing, an outlet from the bottom of saidhopper, connected at its lower end to the blast nozzle and terminatingat its upper end in an orifice spaced above the air pervious partition,whereby the abrasive in said hopper will be fluidized to facilitate itsflow into said outlet orifice, and during continuous operation of saiddevice, the effect of the fiuidizing will be to cause particles ofdebris mixed with the abrasive to settle into the hopper area below saidoutlet orifice and to leave the abrasive above it substantiallyuncontaminated with particles of debris.

2. The device of claim 1 in which said partition is a porous stone.

3. An abrasive impelling device including a source of air under reducedpressure, a blast nozzle in the enclosed work area, a suction trap inthe bottom of Said area, a cyclone connected to said trap, a hopperconnected with and located beneath said cyclone, means connecting saidsource of air to said hopper and to said blast nozzle, wherein anairstream flows to said nozzle, an abrasive inlet tube in said means tointroduce abrasive into said air stream, a housing area in the bottom ofsaid hopper formed by an air pervious partition separating said hopperinto an upper storage area and said housing area, an air inlet into saidhousing area to admit air at atmospheric pressure which will flowupwardly through said partition, said abrasive inlet tube having itsinlet orifice spaced above said partition, said partition having a largenumber of tortuous passageways whereby in continuous operation of saiddevice, the air flowing upwardly through said partition will bothfiuidize said abrasive and will cause any debris returned from said workarea to settle onto said partition below the level of said inlet orificeso it will not be fed back to said blast nozzle.

4. The device as described in claim 3 including a screen member betweensaid cyclone and said hopper to arrest large particles of debris removedby the blast nozzle in the enclosed work area.

Berg Jan. 26, 1954 Mead et al Nov. 20, 1956

